• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2421-2429
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• 2018

Thiol-based self-assembled anchor linked to glucose oxidase (GOx) and gold nanoparticle (GNP) cluster is suggested to enhance the performance of glucose biosensor. By the adoption of thiol-based anchors, the activity of biocatalyst consisting of GOx, GNP, polyethyleneimine (PEI) and carbon nanotube (CNT) is improved because they play a crucial role in preventing the leaching out of GOx. They also promote electron collection and transfer, and this is due to a strong hydrophobic interaction between the active site of GOx and the aromatic ring of anchor, while the effect is optimized with the use of thiophenol anchor due to its simple configuration. Based on that, it is quantified that by the adoption of thiophenol as anchor, the current density of flavin adenine dinucleotide (FAD) redox reaction increases about 42%, electron transfer rate constant ($k_s$) is $9.1{\pm}0.1s^{-1}$ and the value is 26% higher than that of catalyst that does not use the anchor structure.

• Elastomers and Composites
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• 제52권3호
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• pp.173-179
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• 2017

Side-chain liquid crystalline polymers having polysiloxane skeletons were synthesized by a thiol-ene reaction, using two kinds of mesogenic groups: a cholesteryl group for induction into a cholesteric liquid crystal phase and a triazomesogenic group for imparting light-sensitivity. All the synthesized polymers were crystalline, except the one with a single cholesteryl group. Crystallinity, glass transition temperature, and melt transition temperature increased with increasing content of the azomesogenic group. The polymer (P-C10A0) with a single cholesteryl group has a cholesteric phase, the one (P-C0A10) with a single azomesogenic group has a smectic phase, and those with both types of mesogenic groups showed both smectic and cholesteric phases. The temperature ranges of the two liquid crystalline phases in the co-polymers were independent of the contents of the two types of mesogenic groups. The rate of photoisomerization of the light-sensitive azobenzene group in the polymer decreased with increasing azobenzene content due to steric hindrance between the azomesogenic groups.

• Journal of Embryo Transfer
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• 제12권3호
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• pp.277-282
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• 1997

The purpose of this experiment was to determine the effects of thiol compounds, $\beta$-mercaptoethanol($\beta$-ME) and cystearrone with buffalo rat liver cell(BRLC) co-culture on the development and intracellular glutathione(GSH) concentrations of bovine embryos produced by in vitro inaturation(IVM) and in vitro fertilization(IVF). Bovine IVM /IVF embryos developed to 2~8 cell stage were co-cultured with BRLC in GRlaa with or without thiol compounds. The developmental rate beyond morulae stage in CRlaa containing 0, 10,25 and 50$\pi$M $\beta$-ME with BRLG were 63.0, 74.0, 72.3 and 77.1%, respectively. And the developmental rate with 0, 25, 50 and 75$\pi$M cystearnine with BRLC were 69.6, 77.6, 81.0 and 76.8%, respectively. The developmental rate beyond morulae stage of GRlaa containing thiol compound with BRLG group was higher than that of control group. The intracellular GSH concentrations of blastocysts cultured for 5 days in GRlaa containing 0 and 50$\pi$M $\beta$-ME or cysteamine with BRLG were 81.2 and 86.4, 83.2 and 84.2pM, respectively. The intracellular GSH concentrations of blastocysts in GRlaa containing thiol compounds with BRLG was slightly higher than that of control group The cell numbers of blastocysts were not difference in all experimental groups. These results indicate that thiol compounds with BRLG co-culture was increased the percentage of developed into morulae and blastocysts, and intracellular GSII concentrations of blastocysts embryos.

• Biomaterials Research
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• 제22권4호
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• pp.249-258
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• 2018

Background: Mucoadhesive polymers, which may increase the contact time between the polymer and the tissue, have been widely investigated for pharmaceutical formulations. In this study, we developed a new polysaccharide-based mucoadhesive polymer with thermogelling properties. Methods: Hexanoyl glycol chitosan (HGC), a new thermogelling polymer, was synthesized by the chemical modification of glycol chitosan using hexanoic anhydride. The HGC was further modified to include thiol groups to improve the mucoadhesive property of thermogelling HGC. The degree of thiolation of the thiolated HGCs (SH-HGCs) was controlled in the range of 5-10% by adjusting the feed molar ratio. The structure of the chemically modified polymers was characterized by $^1H$ NMR and ATR-FTIR. The sol-gel transition, mucoadhesiveness, and biocompatibility of the polymers were determined by a tube inverting method, rheological measurements, and in vitro cytotoxicity tests, respectively. Results: The aqueous solution (4 wt%) of HGC with approximately 33% substitution showed a sol-gel transition temperature of approximately $41^{\circ}C$. SH-HGCs demonstrated lower sol-gel transition temperatures ($34{\pm}1$ and $31{\pm}1^{\circ}C$) compared to that of HGC due to the introduction of thiol groups. Rheological studies of aqueous mixture solutions of SH-HGCs and mucin showed that SH-HGCs had stronger mucoadhesiveness than HGC due to the interaction between the thiol groups of SH-HGCs and mucin. Additionally, we confirmed that the thermogelling properties might improve the mucoadhesive force of polymers. Several in vitro cytotoxicity tests showed that SH-HGCs showed little toxicity at concentrations of 0.1-1.0 wt%, indicating good biocompatibility of the polymers. Conclusions: The resultant thiolated hexanoyl glycol chitosans may play a crucial role in mucoadhesive applications in biomedical areas.

• Asian-Australasian Journal of Animal Sciences
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• 제32권7호
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• pp.1027-1035
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• 2019

Objective: The aim of this study was to investigate the effects of aged garlic powder (AGP) on physicochemical characteristics, texture profiles, and oxidative stability of ready-to-eat (RTE) pork patties. Methods: There were five treatment groups: a control; 1% fresh garlic powder (T1); 0.5%, 1%, and 2% AGP (T2, T3, and T4). Pork patties with vacuum packaging were roasted at $71^{\circ}C$ for core temperature, stored at $4^{\circ}C$ for 14 d, and then reheated for 1 min using a microwave. Results: The AGP groups showed a lower the level of lipid oxidation and higher thiol contents than the control and T1. The pH value of the control increased whereas that of aged garlic groups decreased after re-heating process. In addition, the redness significantly increased with increasing level of AGP whereas the redness of the control and T1 decreased after reheating process. T4 added patties improved textural and sensory properties compared to the control. Conclusion: The results of this study suggest that AGP addition to RTE pork patties can improve their sensory characteristics and oxidative stability.

• Environmental Engineering Research
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• 제20권4호
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• pp.342-346
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• 2015

Haloacetonitriles (HANs) are nitrogenous disinfection by-products (DBPs) that have been reported to have a higher toxicity than the other groups of DBPs. The adsorption process is mostly used to remove HANs in aqueous solutions. Functionalized composite materials tend to be effective adsorbents due to their hydrophobicity and specific adsorptive mechanism. In this study, the removal of dichloroacetonitrile (DCAN) from tap water by adsorption on thiol-functionalized mesoporous composites made from natural rubber (NR) and hexagonal mesoporous silica (HMS-SH) was investigated. Fourier-transform infrared spectroscopy (FTIR) results revealed that the thiol group of NR/HMS was covered with NR molecules. X-ray diffraction (XRD) analysis indicated an expansion of the hexagonal unit cell. Adsorption kinetic and isotherm models were used to determine the adsorption mechanisms and the experiments revealed that NR/HMS-SH had a higher DCAN adsorption capacity than powered activated carbon (PAC). NR/HMS-SH adsorption reached equilibrium after 12 hours and its adsorption kinetics fit well with a pseudo-second-order model. A linear model was found to fit well with the DCAN adsorption isotherm at a low concentration level.

• Journal of the Korean Chemical Society
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• 제33권1호
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• pp.3-10
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• 1989

In order to obtain a clue in understanding enzymatic hydrolysis in which the His-Cys moieties of papain protease is involved, we prepared cationic peptide-sufactants bearing histidyl, cysteinyl, and both histydyl and cysteinyl residues. Their catalytic efficiency toward the hydrolysis of PNPL were investigated in comicellar phases formed with $N^{+}C_{2}CysC_{12}$, $N^{+}C_{2}HisC_{12}$, $N^{+}C_{2}HisCysC_{12}$ increased markedly in the same order compared with that of $N^{+}C_{2}AlaC_{12}$. The markedly increased catalytic effects are attributed to the imidazole groups of $N^{+}C_{2}HisC_{12}$ and the thiol groups of $N^{+}C_{2}CysC_{12}$, and the large catalytic efficiency of $N^{+}C_{2}HisCysC_{12}$, is considered due to the interaction of the imidazole and the thiol groups. In order to investigate catalytic activities, rate constants for the functional groups, km* and dissociation constants, pKa have been determined. The results showed that $k^{\ast}_m$ and pKa of the imidazole groups were $7.91{\times}10^{-4}S^{-1}$ and 6.49, and those of the thiol groups were $6.00{\times}10^{-4}S^{-1}$ and 10.50. The catalytic effects of comicellar systems on the hydrolysis of p-nitrophenyl esters has increased according to the increasing size of the alkyl carbon number. Therefore, the catalytic effects have been increasing by the interaction of micellar hydrophobic parts and substrates as well as action of the functional groups.

• Journal of Pharmacopuncture
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• 제22권2호
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• pp.109-114
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• 2019

Objectives: Oxidative stress plays a central role in diabetes-induced complications. In the present study, the protevtive effect of Artemisia turanica (A. turanica) was evaluated against diabetes-induced liver oxidative stress and dysfunction. Methods: Fifty male Wistar rats were randomly divided into five groups: control, diabetic, diabetic + metformin, diabetic + A. turanica extract, and diabetic + A. turanica extract + metformin. Experimental diabetes was induced by a single-dose (55 mg/kg, intraperitoneally (ip)) injection of streptozotocin (STZ). Metformin (300 mg/kg) and A. turanica extract (70 mg/kg) were orally administrated three days after STZ injection for four weeks. The levels of malondialdehyde (MDA), total thiol content and superoxide dismutase (SOD) and catalase activities were measured in the liver tissue. Serum glucose concentration, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were also determined. Results: In the diabetic group, serum glucose concentration, serum AST and ALT activities and liver MDA level were significantly higher while tissue total thiol content as well as catalase and SOD activities were lower, compared to the control group. Serum glucose in diabetic rats treated with metformin + A. turanica extract showed a significant decrease compared with the diabetic group. In all the A. turanica extract and metformin treated groups, serum ALT, tissue MDA level, total thiol content and SOD activity significantly improved compared with the diabetic rats. However, treatment of the diabetic rats only with metformin could not significantly change the activities of catalase and AST compared with the diabetic group. Conclusion: These findings suggested that A. turanica extract had a therapeutic effect on liver dysfuncyion and oxidative stress induced by diabetes, that may be probably due to its antioxidant and antiinflammatory effects.

• Journal of Microbiology and Biotechnology
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• 제23권2호
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• pp.205-210
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• 2013

Thiol-ene polymerization is a versatile tool for several applications. Here we report the preparation of epoxide groups containing thiol-ene photocurable polymeric support and the covalent immobilization of ${\alpha}$-amylase onto these polymeric materials. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) coupled with SEM was used to explore the chemical composition. The polymeric support and the immobilization of the enzyme were characterized by FTIR analysis. SEM-EDS and FTIR results showed that the enzyme was successfully covalently attached to the polymeric support. The immobilization efficiency and enzyme activity of ${\alpha}$-amylase were examined at various pH (5.0-8.0) and temperature ($30-80^{\circ}C$) values. The storage stability and reusability of immobilized ${\alpha}$-amylase were investigated. The immobilization yield was $276{\pm}1.6$ mg per gram of polymeric support. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermostability than the free one. The storage stability and reusability were improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 86.7% of its activity after 30 days. These results confirm that ${\alpha}$-amylase was successfully immobilized and gained a more stable character compared with the free one.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.1092-1096
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• 2020

YjiC, a glycosyltransferase from Bacillus licheniformis, is a well-known versatile enzyme for glycosylation of diverse substrates. Although a number of O-glycosylated products have been produced using YjiC, no report has been updated for nucleophilic N-, S-, and C- glycosylation. Here, we report the additional functional capacity of YjiC for nucleophilic N- and S- glycosylation using a broad substrate spectrum including UDP-α-D-glucose, UDP-N-acetyl glucosamine, UDP-N-acetylgalactosamine, UDP-α-D-glucuronic acid, TDP-α-L-rhamnose, TDP-α-D-viosamine, and GDP-α-L-fucose as donor and various amine and thiol groups containing natural products as acceptor substrates. The results revealed YjiC as a promiscuous enzyme for conjugating diverse sugars at amine and thiol functional groups of small molecules applicable for generating glycofunctionalized chemical diversity libraries. The glycosylated products were analyzed using HPLC and LC/MS and compared with previous reports.